From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1653C4363D for ; Tue, 22 Sep 2020 07:23:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 55F5D2145D for ; Tue, 22 Sep 2020 07:23:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 55F5D2145D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arndb.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AE12F6B00D9; Tue, 22 Sep 2020 03:23:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A6AC26B00DB; Tue, 22 Sep 2020 03:23:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 95F326B00DD; Tue, 22 Sep 2020 03:23:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0019.hostedemail.com [216.40.44.19]) by kanga.kvack.org (Postfix) with ESMTP id 7C3856B00D8 for ; Tue, 22 Sep 2020 03:23:58 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 355C4180AD811 for ; Tue, 22 Sep 2020 07:23:58 +0000 (UTC) X-FDA: 77289858156.02.fight43_2302b882714b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id F0968100B5DE2; Tue, 22 Sep 2020 07:23:57 +0000 (UTC) X-HE-Tag: fight43_2302b882714b X-Filterd-Recvd-Size: 5316 Received: from mout.kundenserver.de (mout.kundenserver.de [217.72.192.73]) by imf44.hostedemail.com (Postfix) with ESMTP; Tue, 22 Sep 2020 07:23:56 +0000 (UTC) Received: from mail-qv1-f49.google.com ([209.85.219.49]) by mrelayeu.kundenserver.de (mreue108 [212.227.15.145]) with ESMTPSA (Nemesis) id 1MdNPq-1ktgM70iS8-00ZNxK; Tue, 22 Sep 2020 09:23:55 +0200 Received: by mail-qv1-f49.google.com with SMTP id q10so8986257qvs.1; Tue, 22 Sep 2020 00:23:54 -0700 (PDT) X-Gm-Message-State: AOAM532sYTAgtsdjZe3GzxwYow9v+Td0hY6NiHO5hsRGyy/hirVqGYsr 6qY5zVCBiXApB/g0QicyaR4twpaL7+S7a82RdQ8= X-Google-Smtp-Source: ABdhPJx2+lYoTA/KUzOktg9GCEROrxWzhLaiei0nYKlXvAWkeVBXqnjogbknJct+KWfdqdHtsSEC4gKbjbjELvczheY= X-Received: by 2002:ad4:4594:: with SMTP id x20mr4471122qvu.4.1600759433835; Tue, 22 Sep 2020 00:23:53 -0700 (PDT) MIME-Version: 1.0 References: <563138b5-7073-74bc-f0c5-b2bad6277e87@gmail.com> <486c92d0-0f2e-bd61-1ab8-302524af5e08@gmail.com> In-Reply-To: From: Arnd Bergmann Date: Tue, 22 Sep 2020 09:23:37 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag To: Pavel Begunkov Cc: Andy Lutomirski , Christoph Hellwig , Al Viro , Andrew Morton , Jens Axboe , David Howells , linux-arm-kernel , X86 ML , LKML , "open list:MIPS" , Parisc List , linuxppc-dev , linux-s390 , sparclinux , linux-block , Linux SCSI List , Linux FS Devel , linux-aio , io-uring@vger.kernel.org, linux-arch , Linux-MM , Network Development , keyrings@vger.kernel.org, LSM List Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K1:JjHO07XMHFcaMzRqfv6eND2vNCF+cXpp9nNYhS/7TVuZ37j7gpy d7mhNWJqJcCe9ce/fVlNIoR8TOfopgUmrd6Ad548UStVIuo5Ay3GKvmEIqX9M9Qut/8QrTS A3L5ffTK/nk80Fq40r6sZlQKT5KHEyVZw7wciz+r71zlShkCaPQOFdsuxW9mc1fAjK9mS7e BK3hTQqqkNxgerFlS9yZA== X-UI-Out-Filterresults: notjunk:1;V03:K0:4CQLG5ZXm9Y=:ddcUvW+vGwIJmpVZpBByel JeMai/ALaJhMibpmyfhuh2fBdvQGxjJpxyUYfW2H/QZyEKoKW5Hum6JoF3dMr1qMrtaFoj2zU Hg3Umf4QR/W0nM9R/uH0nWvUcDFVApmmi+/JQp3UBch7wCSG8pusxedT13JNjvelZudw9mv7i dor0Pns4dofjxraTHmG+2i2SFaQ/SD3NAg4uLL+Hlu2OB0Ll4SLFtl6PJ+kC/P2h1hWwWhpm1 Vx3zWfqWdIZg/mKlLVDhWSYsQVFnLx1aHuv+2qSUx6VIC4PLxwbHIeTkstwc7xgUY/CQvD9KJ q7DDj78ugug9xbMbuBQpeJQw12n1HbOzRqP7JFufG400Te2/RnxezW7Nox7BcbkFsfYpJxcQV yZ/MobgIaID6KPsWaDyB3n1pGcZGDRdXjTsFlXfytDC3IYmT439Sxj3LLhRmQJmOsLOFwFRNd bh3jmE1bzjmRb45MkT6SY1Ywf1u/d9oj+NOPOCMztGGRKHsWxrSFMuduyfQ1zTbChtzsDOYtA NvgBWzMcCdBxPbFp6teQwHC4iXIRGpT5MpV/vU9fcFcOPu/4erlWjMcVAIYiMRo/Ht1+F0SdG /Wi+CAP34VPtCwHEs9d2Co9nJuiHb8bILnNIap5oVr7lH5L3UTgd6BdlVLdqn/4979mvlPdc1 G8Fw69EA/5XkOBqHwdrP/zOb10bT6tSvgi+20kDBIrQn3ZWF+wnhM3t+Md83SVWeF8VDtKBdb ZcgWuRDG00SLDdqfHDWR6D20trr+lt+xorh9FUjnnGxdKdqcu6nm1els6ILGRwzPGgwHFQcGv KL8H1M7U2DSQe0h5ZwG6/iH0oPuEz2CEYJ6Ihz39nubBdApHrDPcP4czS+Tpb6NYW0+gmya X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Sep 22, 2020 at 8:32 AM Pavel Begunkov wrote: > On 22/09/2020 03:58, Andy Lutomirski wrote: > > On Mon, Sep 21, 2020 at 5:24 PM Pavel Begunkov wrote: > > I may be looking at a different kernel than you, but aren't you > > preventing creating an io_uring regardless of whether SQPOLL is > > requested? > > I diffed a not-saved file on a sleepy head, thanks for noticing. > As you said, there should be an SQPOLL check. > > ... > if (ctx->compat && (p->flags & IORING_SETUP_SQPOLL)) > goto err; Wouldn't that mean that now 32-bit containers behave differently between compat and native execution? I think if you want to prevent 32-bit applications from using SQPOLL, it needs to be done the same way on both to be consistent: if ((!IS_ENABLED(CONFIG_64BIT) || ctx->compat) && (p->flags & IORING_SETUP_SQPOLL)) goto err; I don't really see how taking away SQPOLL from 32-bit tasks is any better than just preventing access to the known-broken files as Al suggested, or adding the hack to make it work as in Christoph's original patch. Can we expect all existing and future user space to have a sane fallback when IORING_SETUP_SQPOLL fails? Arnd